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INTRODUCTION.

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Presentation on theme: "INTRODUCTION."— Presentation transcript:

1 INTRODUCTION

2 CHEMISTRY The science that deals with the materials of the universe and the changes that these materials undergo Wood burns Plants grow Iron rusts Bread bakes Human digestion

3 The Scientific Method State the problem Make observations
Form a hypothesis Perform an experiment Develop a Law A summary of observed behavior Develop a theory An explanation of behavior Continue to experiment Modify theory as needed

4 Important Terms Matter Mass Volume Qualitative observations
Anything that has mass and volume Mass Amount of matter in an object Volume Amount of space an object occupies Qualitative observations Observations not requiring measurements Quantitative observations Observations requiring measurements

5 Classification of matter
has mass and volume PURE SUBSTANCES Can write chemical formula ELEMENT One type of atom COMPOUND Two or more different atoms chemically bonded MIXTURES Variable ratio HOMOGENEOUS solutions HETEROGENEOUS Colloids and suspensions

6 Energy All objects possess energy
An object has two general forms of energy Potential energy The energy of an object due to its position Kinetic energy The energy possessed by an object due to its motion Law of conservation of energy Energy is neither created or destroyed Energy can be converted from one form to another

7 PHASES OF MATTER Solid Liquid Gas Definite volume and shape
Definite volume but takes shape of container Gas No definite volume and no definite shape

8 Physical and Chemical Properties and Changes
Physical Property Characteristics that describe a substance Physical Change A change that does not affect the composition of the substance Chemical Property Characteristics that refer to the ability to form new substances Chemical Change A change which produces new substances

9 Measurements

10 SIGNIFICANT FIGURES The reliable digits in a measurement based on the measuring instrument Atlantic-Pacific Method A = decimal Absent, begin counting from right P = decimal Present, begin counting from left

11 TRY THESE 1,000 1 sig fig 0.001 0.0010 2 sig fig 1000.0 5 sig fig

12

13 Rules for Using Sig Figs
Multiplication/Division The number of sig figs in the result is the same as that in the measurement with the smallest number of sig figs 4.56 x = or 6.4 8.315/298 = or Addition/Subtraction The limiting term is the one with the smallest number of decimal places = or 31.1

14 where 1.00 ≥ M < 10 and n is an integer
SCIENTIFIC NOTATION The expression of numbers in terms of M x 10n where 1.00 ≥ M < 10 and n is an integer

15 TRY THESE 25,000 2.5 X 104 X 0.0100 X

16 ACCURACY/PRECISION Accuracy Precision
How close a measurement is to the actual value Precision How close a set of measurements are to each other

17 Dartboard analogy

18 DENSITY Mass Volume Density
Amount of matter in an object Volume Amount of space an object occupies Density Mass per unit volume Percent Error = /actual-experimental/ x 100 actual

19 Formula for density What is the density of an object with a mass of 7.65 g and a volume of 4.5 mL?

20 Factor Labeling/Dimensional Analysis
1 in = 2.54 cm ft = 1 mi Convert 3.1 miles to kilometers

21 1 kg = 2.2 lbs Convert 3.3 lbs to grams

22 Convert 8.00 km to miles

23 CHEMICAL REACTIONS Chemical Reaction Reactant Product
A change in which one or more substances are changed into one or more new substances Reactant A starting substance in a chemical reaction Product A substance produced as the result of a chemical change


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